Itch Evoked by Electrical Stimulation of the Skin

Tuckett, Robert P.

doi:10.1111/1523-1747.ep12529734

Cited by 102 publications

(51 citation statements)

References 40 publications

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“…Accordingly, it was postulated that pain and itch might be encoded by distinct firing patterns of C-fibers (81). However, this theory was disputed by human studies showing no correlation between firing patterns and the senses of pain versus itch (82,103). Second, CMH neurons can be divided into quickly adapting (QC) and slowly adapting (SC) subtypes (27).…”

Section: The Coding Of Pain Versus Itchmentioning

confidence: 99%

Labeled lines meet and talk: population coding of somatic sensations

Ma¹

2010

J. Clin. Invest.

145

121

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The somatic sensory system responds to stimuli of distinct modalities, including touch, pain, itch, and temperature sensitivity. In the past century, great progress has been made in understanding the coding of these sensory modalities. From this work, two major features have emerged. First, there are specific neuronal circuits or labeled lines transmitting specific sensory information from the skin to the brain. Second, the generation of specific sensations often involves crosstalk among distinct labeled lines. These features suggest that population coding is the mechanism underlying somatic sensation.

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Section: The Coding Of Pain Versus Itchmentioning

confidence: 99%

Labeled lines meet and talk: population coding of somatic sensations

Ma¹

2010

J. Clin. Invest.

145

121

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“…Cowhage (which consists of trichomes covering the pod of the tropical legume Mucuna pruriens) has long been used in the production of experimental itch. A single trichome can produce an intense itch lasting several minutes that begins shortly after insertion into the skin (Graham et al, 1951;Shelley and Arthur, 1957;Tuckett, 1982). An early biochemical study by Shelley and Arthur, (1955) indicated that cowhage spicules contain an itchproducing proteinase they named mucunain.…”

Section: Introductionmentioning

confidence: 99%

The Itch-Producing Agents Histamine and Cowhage Activate Separate Populations of Primate Spinothalamic Tract Neurons

Davidson¹,

Zhang²,

Yoon³

et al. 2007

J. Neurosci.

224

184

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Itch is an everyday sensation, but when associated with disease or infection it can be chronic and debilitating. Several forms of itch can be blocked using antihistamines, but others cannot and these constitute an important clinical problem. Little information is available on the mechanisms underlying itch that is produced by nonhistaminergic mechanisms. We examined the responses of spinothalamic tract neurons to histaminergic and, for the first time, nonhistaminergic forms of itch stimuli. Fifty-seven primate spinothalamic tract (STT) neurons were identified using antidromic activation techniques and examined for their responses to histamine and cowhage, the nonhistaminergic itch-producing spicules covering the pod of the legume Mucuna pruriens. Each examined neuron had a receptive field on the hairy skin of the hindlimb and responded to noxious mechanical stimulation. STT neurons were tested with both pruritogens applied in a random order and we found 12 that responded to histamine and seven to cowhage. Each pruritogen-responsive STT neuron was activated by the chemical algogen capsaicin and two-thirds responded to noxious heat stimuli, demonstrating that these neurons convey chemical, thermal, and mechanical nociceptive information as well. Histamine or cowhage responsive STT neurons were found in both the marginal zone and the deep dorsal horn and were classified as high threshold and wide dynamic range. Unexpectedly, histamine and cowhage never activated the same cell. Our results demonstrate that the spinothalamic tract contains mutually exclusive populations of neurons responsive to histamine or the nonhistaminergic itch-producing agent cowhage.

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“…The sensation induced by capsaicin applied topically was, however, characterized by burning, itching, and stinging. In addition to constituting indirect evidence that capsaicin does not strongly stimulate the warmth sense, these sensation qualities also raise the possibility that the chemical stimulates afferent fibers other than those typically activated by changes in temperature (e.g., specific "itch" fibers, if they exist; see Tuckett, 1982;Tuckett & Wei, 1987). Evidence from studies in both humans and monkeys indicate that intradermal injection of capsaicin stimulates c-polymodal afferents much less vigorously than does more superficial administration, yet intense burning sensations can result from both modes of application (Simone, Ngeow, Whitehouse, et al, 1987).…”

mentioning

confidence: 99%

Spatial summation of chemical irritation and itch produced by topical application of capsaicin

Green

1990

Perception & Psychophysics

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The effect of increasing the total area of stimulation on the sensations of irritation produced by topical application of capsaicin was studied in two experiments. In the first experiment, stimulus area was varied by changing the size of filter paper disks on which capsaicin was delivered to the skin of the forearm. Subjects rated the intensity and quality of the cutaneous sensations over a 15-min period. Increasing stimulus area by a factor of 15 resulted in a relatively modest increase in the peak perceived intensity of irritation, a shortening of the latency to the onset of irritation, and shifts in the frequency of reports of sensations of itching and stinging/pricking. However, itch was the most frequently reported sensation regardless of stimulus size. In Experiment 2, stimulus area was manipulated by varying the number of stimuli applied to the skin. Despite a smaller difference in total stimulus areas (9-fold vs. 15-fold),the difference in perceived irritation was more pronounced than it was in Experiment 1 and reached statistical significance. It is therefore concluded that spatial summation does occur in the afferent system or systems responsible for the perception of capsaicin on the skin. This result is consistent with previous reports of summation at the threshold for heat pain and constitutes new information about the spatial integration of pruritic stimulation.Spatial summation is a common property of the cutaneous senses. Enlarging the area of stimulation has been shown to increase the sensitivity of the skin to vibration

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Itch Evoked by Electrical Stimulation of the Skin

Cited by 102 publications

References 40 publications

Labeled lines meet and talk: population coding of somatic sensations

Labeled lines meet and talk: population coding of somatic sensations

The Itch-Producing Agents Histamine and Cowhage Activate Separate Populations of Primate Spinothalamic Tract Neurons

Spatial summation of chemical irritation and itch produced by topical application of capsaicin

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